Treatment of gastric eosinophilia by epicutaneous immunotherapy in piglets sensitized to peanuts

Triggers for eosinophilic esophagitis (EoE): The intersection of food allergy and EoE

Eosinophilic esophagitis and IgE-mediated food allergy are both food-triggered diseases that are increasing in prevalence. They share many clinical links, including significant comorbidity and similar food triggers, and as atopic diseases, they likely share upstream mechanisms related to barrier function and signals leading to TH2 skewing. In this review, we focus on links between eosinophilic esophagitis and IgE-mediated food allergy with an emphasis on what insights may be derived from overlapping food triggers and immune phenotypes. Through further investigation of these connections, we may be able to better understand not only IgE-mediated food allergy and eosinophilic esophagitis but also general atopic response to food proteins and evolution of allergic response to food.

Recent advances in epicutaneous immunotherapy and potential applications in food allergy

Given the potent immunological properties of the skin, epicutaneous immunotherapy (EPIT) emerges as a promising treatment approach for inducing immune tolerance, particularly for food allergies. Targeting the highly immunocompetent, non-vascularized epidermis allows for the application of microgram amounts of allergen while significantly reducing the risk of allergen passage into the bloodstream, thus limiting systemic allergen exposure and distribution. This makes EPIT highly suitable for the treatment of potentially life-threatening allergies such as food allergies. Multiple approaches to EPIT are currently under investigation for the treatment of food allergy, and these include the use of allergen-coated microneedles, application of allergen on the skin pretreated by tape stripping, abrasion or laser-mediated microperforation, or the application of allergen on the intact skin using an occlusive epicutaneous system. To date, the most clinically advanced approach to EPIT is the Viaskin technology platform. Viaskin is an occlusive epicutaneous system (patch) containing dried native allergen extracts, without adjuvants, which relies on frequent application for the progressive passage of small amounts of allergen to the epidermis through occlusion of the intact skin. Numerous preclinical studies of Viaskin have demonstrated that this particular approach to EPIT can induce potent and long-lasting T-regulatory cells with broad homing capabilities, which can exert their suppressive effects in multiple organs and ameliorate immune responses from different routes of allergen exposure. Clinical trials of the Viaskin patch have studied the efficacy and safety for the treatment of life-threatening allergies in younger patients, at an age when allergic diseases start to occur. Moreover, this treatment approach is designed to provide a non-invasive therapy with no restrictions on daily activities. Taken together, the preclinical and clinical data on the use of EPIT support the continued investigation of this therapeutic approach to provide improved treatment options for patients with allergic disorders in the near future.

Treating allergies via skin - Recent advances in cutaneous allergen immunotherapy

Subcutaneous allergen immunotherapy has been practiced clinically for decades to treat airborne allergies. Recently, the cutaneous route, which exploits the immunocompetence of the skin has received attention, which is evident from attempts to use it to treat peanut allergy. Delivery of allergens into the skin is inherently impeded by the barrier imposed by stratum corneum, the top layer of the skin. While the stratum corneum barrier must be overcome for efficient allergen delivery, excessive disruption of this layer can predispose to development of allergic inflammation. Thus, the most desirable allergen delivery approach must provide a balance between the level of skin disruption and the amount of allergen delivered. Such an approach should aim to achieve high allergen delivery efficiency across various skin types independent of age and ethnicity, and optimize variables such as safety profile, allergen dosage, treatment frequency, application time and patient compliance. The ability to precisely quantify the amount of allergen being delivered into the skin is crucial since it can allow for allergen dose optimization and can promote consistency and reproducibility in treatment response. In this work we review prominent cutaneous delivery approaches, and offer a perspective on further improvisation in cutaneous allergen-specific immunotherapy.

Immunologic and pathologic characterization of a novel swine biomedical research model for eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergy-mediated condition with an increasing incidence in both children and adults. Despite EoE's strong impact on human health and welfare, there is a large unmet need for treatments with only one recently FDA-approved medication for EoE. The goal of this study was to establish swine as a relevant large animal model for translational biomedical research in EoE with the potential to facilitate development of therapeutics. We recently showed that after intraperitoneal sensitization and oral challenge with the food allergen hen egg white protein (HEWP), swine develop esophageal eosinophilia-a hallmark of human EoE. Herein, we used a similar sensitization and challenge treatment and evaluated immunological and pathological markers associated with human EoE. Our data demonstrate that the incorporated sensitization and challenge treatment induces (i) a systemic T-helper 2 and IgE response, (ii) a local expression of eotaxin-1 and other allergy-related immune markers, (iii) esophageal eosinophilia (>15 eosinophils/0.24 mm²), and (iv) esophageal endoscopic findings including linear furrows and white exudates. Thereby, we demonstrate that our sensitization and oral challenge protocol not only induces the underlying immune markers but also the micro- and macro-pathological hallmarks of human EoE. This swine model for EoE represents a novel relevant large animal model that can drive translational biomedical research to develop urgently needed treatment strategies for EoE.

Diversity of T cells in the skin: Novel insights

T cells populate the skin to provide an effective immunosurveillance against external insults and to maintain tissue homeostasis. Most cutaneous T cells are αβ T cells, however, γδ T cells also exist although in much lower frequency. Different subsets of αβ T cells can be found in the skin, such as short-lived effector T cells, central memory T cells, effector memory T cells, and tissue-resident memory T cells. Their differential biology, function, and location provide an ample spectrum of immune responses in the skin. Foxp3+ memory regulatory T cells have a pivotal role in maintaining homeostasis in the skin and their dysregulation has been linked with different skin pathologies. The skin also contains populations of non-classical T cells, such as γδ T cells, NK T cells, and MR1-restricted T cells. Their role in skin homeostasis and response to pathogens has been well established in the past years, however, there is also growing evidence of their role in mediating allergic skin inflammation and promoting sensitization to allergens. In this review, we provide an updated overview on the different subsets of T cells that populate the skin with a specific focus on their role in allergic skin inflammation.

AIT: New Avenues in Allergen Immunotherapy

During the last decades a substantial increase of allergic diseases has been noticed including allergic asthma and rhinoconjunctivitis as well as food allergies. Since efficient avoidance of airborne - and often hidden - food allergens is not possible, allergen immunotherapy (AIT) is the only causative treatment with the goal of inducing allergen tolerance in affected individuals. Efficacy as well as safety of AIT significantly depends on how the allergen is presented to the immune system, meaning both the route and the form of its application. Here, new ways of allergen administration have lately been explored, some of which are auspicious candidates for successful implementation in the therapeutic management of immediate-type allergies. While the first oral AIT has been approved recently by the FDA for the treatment of peanut allergy, further interesting routes of allergen application include either epicutaneous, intradermal, intranasal, or intralymphatic delivery. Besides, rather the immunologically relevant peptides instead of whole allergen may be administered to develop tolerance. In this chapter, we will describe these new and promising avenues of allergen application in the field of AIT. In addition, we will discuss their potential for future treatment of IgE-mediated allergic diseases enhancing therapeutic efficiency while further minimizing the risks of adverse events.

Eosinophilic gastrointestinal disorders and allergen immunotherapy: Lights and shadows

Allergic diseases, such as IgE-mediated food allergy, asthma, and allergic rhinitis, are relevant health problems worldwide and show an increasing prevalence. Therapies for food allergies are food avoidance and the prompt administration of intramuscular epinephrine in anaphylaxis occurring after accidental exposure. However, allergen immunotherapy (AIT) is being investigated as a new potential tool for treating severe food allergies. Effective oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT) induce desensitization and restore immune tolerance to the causal allergen. While immediate side effects are well known, the long-term effects of food AIT are still underestimated. In this regard, eosinophilic gastrointestinal disorders (EGIDs), mainly eosinophilic esophagitis, have been reported as putative complications of OIT for food allergy and sublingual immunotherapy (SLIT) for allergic asthma and rhinitis. Fortunately, these complications are usually reversible and the patient recovers after AIT discontinuation. This review summarizes current knowledge on the possible causative link between eosinophilic gastrointestinal disorders and AIT, highlighting recent evidence and controversies.

Swine as biomedical animal model for T-cell research-Success and potential for transmittable and non-transmittable human diseases

Swine is biologically one of the most relevant large animal models for biomedical research. With its use as food animal that can be exploited as a free cell and tissue source for research and its high susceptibility to human diseases, swine additionally represent an excellent option for both the 3R principle and One Health research. One of the previously most limiting factors of the pig model was its arguably limited immunological toolbox. Yet, in the last decade, this toolbox has vastly improved including the ability to study porcine T-cells. This review summarizes the swine model for biomedical research with focus on T cells. It first contrasts the swine model to the more commonly used mouse and non-human primate model before describing the current capabilities to characterize and extend our knowledge on porcine T cells. Thereafter, it not only reflects on previous biomedical T-cell research but also extends into areas in which more in-depth T-cell analyses could strongly benefit biomedical research. While the former should inform on the successes of biomedical T-cell research in swine, the latter shall inspire swine T-cell researchers to find collaborations with researchers working in other areas - such as nutrition, allergy, cancer, transplantation, infectious diseases, or vaccine development.

Efficacy of Epicutaneous Immunotherapy in Children With Milk-Induced Eosinophilic Esophagitis

BACKGROUND & AIMS

Eosinophilic esophagitis (EoE) is caused by an immune response to specific food allergens. There are no approved therapies beyond avoidance of the allergen(s) or treatment of inflammation. Epicutaneous immunotherapy (EPIT) reduces features of eosinophilic gastrointestinal disease in mice and pigs. We performed randomized, placebo-controlled study to determine the safety and efficacy of EPIT with Viaskin milk in children with milk-induced EoE.

METHODS

In a double-blind study, 20 children (4-17 years old) with milk-induced EoE were randomly assigned to groups given EPIT with Viaskin milk (n = 15) or placebo (n = 5) for 9 months during a milk-free period, followed by milk-containing diet for 2 months with EPIT. Then, subjects underwent upper endoscopy analysis, biopsies were collected, and maximum esophageal eosinophil counts were determined and was the primary endpoint. After upper endoscopy, patients were given open-label EPIT for 11 months (open-label phase). The subjects were allowed to consume milk if they had maximum values of fewer than 10 eosinophils/high-power field (eos/hpf); otherwise, they remained on a milk-free diet until the last 2 months of the open-label phase.

RESULTS

In the intent to treat population, there was no significant difference between the Viaskin milk group in mean eos/hpf (50.1 ± 43.97 eos/hpf) vs the placebo group (48.20 ± 56.98 eos/hpf). However, in the per-protocol population (7 patients given Viaskin milk and 2 patients given placebo), patients given Viaskin milk patients had a significantly lower mean eos/hpf count (25.57 ± 31.19) than patients given placebo (95.00 ± 63.64) (p = .038). At the end of the open-label phase, 9 of 19 evaluable subjects had mean values of fewer than 15 eos/hpf (47% response). The number of adverse events did not differ significantly between the Viaskin milk and placebo groups; there was 1 serious adverse event in the placebo group.

CONCLUSIONS

In a pilot study of pediatric patients with EoE given EPIT with Viaskin milk or placebo for 11 months, we found no significant difference between groups for the maximum eosinophil count at the end of the study. However, findings from a per-protocol analysis indicate that Viaskin milk can reduce eos/hpf. At study completion, 47% of patients who continued open-label Viaskin milk for an additional 11 months had mean values of fewer than 15 eos/hpf. ClinicalTrials.gov no: NCT02579876.

Oesophageal eosinophilia accompanies food allergy to hen egg white protein in young pigs

BACKGROUND

Esophagitis with eosinophilia, inflammation, and fibrosis represent a chronic condition in humans with food allergies.

OBJECTIVE

In this investigation, we asked whether esophagitis with an eosinophilic component is observed in young pigs rendered allergic to hen egg white protein (HEWP).

METHODS

Food allergy was induced in young pigs using two protocols. In one protocol, sensitized pigs were challenged by gavage with a single dose of HEWP. Clinical signs were monitored for 24 hours, and then, gastrointestinal (GI) tissues were collected for histological examination. The phenotype of circulating, ovalbumin (OVA)-specific T cells also was examined in HEWP challenged animals. In the second protocol, sensitized animals were fed HEWP for 28 days. Animals were then examined by endoscopy and gastrointestinal tissues collected for histological examination.

RESULTS

In pigs challenged by gavage with HEWP, clinical signs were noted in 5/6 pigs including diarrhoea, emesis, and skin rash. Clinical signs were not seen in any control group. Histological analysis revealed significant levels of oesophageal eosinophilic infiltration (P < .05) in 4/6 of these animals, with two also displaying eosinophilic infiltration in the stomach. Eosinophils were not increased in ileum or colon samples. Increased numbers of circulating, OVA-specific CD4+ T cells also were observed in pigs that received HEWP by gavage. In the group of animals fed HEWP, endoscopy revealed clinical signs of esophagitis including oedema, granularity, white spots, and furrowing, while histology revealed oedema, immune cell infiltration, and basal zone hyperplasia.

CONCLUSIONS AND CLINICAL RELEVANCE

Food allergy in the pig can be associated with esophagitis based on histological and endoscopic findings, including eosinophilic infiltration. The young pig may, therefore, be a useful large animal model for the study of eosinophilic esophagitis in humans.

Regional Differences in Food Allergies

The prevalence of food allergies is increasing worldwide. To understand the regional specificities of food allergies and develop effective therapeutic interventions, extensive regional epidemiological studies are necessary. While data regarding incidence, prevalence, regional variation, and treatment in food allergies are available for western countries, such studies may not be available in many Asian countries. China accounts for almost 20% of the world's population and has a vast ethnic diversity, but large-scale meta-analyses of epidemiological studies of food allergy in China are lacking. A literature search revealed 22 publications on the prevalence of food allergy in Chinese populations. A review of these studies showed that the prevalence of food allergies in China is comparable to that in western countries, even though the Chinese diet is vastly different from that of the West and may vary even greatly within China, and finally, specific antigenic triggers of food allergy vary between China and the West and also within China. Current clinical management of food allergy in China includes allergen-specific immunotherapy, Chinese herbal medicine, acupuncture, and Western medicine. This study demonstrates an unmet need in China for a thorough investigation of the prevalence of food allergies in China, the specific foods involved, and characterization of the specific antigenic triggers of food allergy with respect to ethnicity, age, and diet in China.

The Efficacy and Safety of Epicutaneous Immunotherapy for Allergic Diseases: A Systematic Review and Meta-Analysis

OBJECTIVES

To systematically review the effect and safety of epicutaneous immunotherapy (EPIT) for allergic diseases.

METHODS

We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, CQ VIP Database, Wanfang Data, and international trial register from their inception to July 29, 2019, without language restrictions, for randomized controlled trials (RCTs) that compared EPIT versus no EPIT for allergen-triggered allergic reactions. We assessed certainty of evidence by the GRADE approach.

RESULTS

Ten RCTs with 1,085 participants (aged from 10 months to 65 years) comparing EPIT with placebo for peanut, cow milk, or grass-pollen allergy met the eligibility criteria. A substantial benefit in terms of desensitization in EPIT group was more likely for peanut or cow milk protein allergy (risk ratio [RR] 2.34, 95% CI 1.69-3.23; I2 = 0%; high certainty evidence). EPIT increased local-treatment-related adverse events (L-TRAE; RR 1.56, 95% CI 1.03-2.36; I2 = 82%; moderate certainty evidence). But there were no significantly increased risk of any TRAEs (low certainty evidence) or systemic-TRAEs (S-TRAEs; very low certainty evidence) in EPIT group. The incidence rate of serious AEs, the use of rescue medications, and anaphylactic reactions stratified by organ systems including skin and mucosa, eyes and upper respiratory, lower respiratory, and gastrointestinal system in EPIT group were similar to placebo group. In subgroup analysis, desensitization of EPIT was significantly effective in peanut allergy (RR 2.29, 95% CI 1.64-3.21; I2 = 0%) and children <12 years (RR 2.85, 95% CI 1.92-4.24; I2 = 0%) with high certainty evidence. Only epicutaneous grass-pollen immunotherapy significantly increased the risk of S-TRAE (RR 4.65, 95% CI 1.10-19.64; I2 = 0%).

CONCLUSION

The systematic review suggests that EPIT might induce desensitization in peanut allergy and an increased risk of local AEs. These findings should be interpreted with caution owing to the limited study and heterogeneity. More data in the older (children ≥12 years and adults) and other allergic diseases are needed.

Future therapies for eosinophilic gastrointestinal disorders

OBJECTIVE

To review novel therapeutics in development for treatment of eosinophilic gastrointestinal disorders (EGIDs).

DATA SOURCES

Clinical trial data (clinicaltrials.gov) and literature search on PubMed.

STUDY SELECTIONS

Studies on treatment and clinical trials in EGIDs were included in this review.

RESULTS

During the past decade, significant progress has been made in understanding disease mechanisms in EGIDs. As a result, a variety of novel therapeutics have been developed for treatment of these disorders. Several monoclonal antibodies against targets, including interleukin (IL) 4, IL-5, IL-13, integrins, and siglec-8, have shown promise in early trials. Novel formulations of corticosteroids are also in development.

CONCLUSION

The field of EGID research has advanced rapidly, and disease-modifying therapeutics are closer to clinical application.

Could This Be IT? Epicutaneous, Sublingual, and Subcutaneous Immunotherapy for the Treatment of Food Allergies

PURPOSE OF REVIEW

Over the last decade, there has been a spark in innovation in the development of therapies for food allergy. Herein, we describe the background and recent advances for food-specific immunotherapies including epicutaneous (EPIT), sublingual (SLIT), and subcutaneous (SCIT).

RECENT FINDINGS

Studies have progressed most quickly for the treatment of peanut allergy. Data from the phase 3 EPIT trial add to the accumulating evidence that this will be a viable therapy for peanut allergy. Studies for SLIT and SCIT remain in earlier phases with promising results. This is an exciting era for the treatment of food allergy. Multiple therapies are under investigation, each with their own potential advantages. Specific strengths and limitations of each of these therapies may provide an opportunity to personalize the choice of therapy for individual patients.

Developments in the field of allergy in 2017 through the eyes of Clinical and Experimental Allergy

In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2017. Experimental models of allergic disease, basic mechanisms, clinical mechanisms, allergens, asthma and rhinitis and clinical allergy are all covered.

Epicutaneous immunotherapy in rhino-conjunctivitis and food allergies: a review of the literature

Background

Epicutaneous immunotherapy (EPIT) is a new way of allergen administration that has a high rate of adherence and safety. The aim of this manuscript is to review clinical trials on EPIT for respiratory and food allergies published in the last 10 years, taking into account how different variables (i.e., dose, patch application duration, skin preparation, and efficacy and safety evaluation) have influenced study results.

Main body

From a review of the literature, we identified eight placebo-controlled, double-blind trials conducted on children and adults, including four studies on grass pollen rhino-conjunctivitis, one on cow’s milk allergy and three on peanut allergy. Different methods for skin pre-treatment, such as skin abrasion and tape stripping or stratum corneous hydration by an occlusive system, different endpoints and cumulative allergen doses, and different durations of patch application and tape stripping, were used in the rhino-conjunctivitis studies. A visual analogue system was used for the efficacy evaluation. Several local skin reactions (eczema) and some systemic adverse reactions were reported at higher rates in the active group compared to placebo in one study, but this was not shown by other authors. Local eczema reactions were correlated to the times for applying the tape stripping, while systemic side effects were correlated to the deepness of scraping. In the food allergy trials, differences in the food challenge thresholds, endpoints and allergen sites of the cutaneous patch application influenced the study results. A slight dose-dependent efficacy was found in the peanut allergy studies, which was confirmed by a more significant increase in the following progressive open study. Few adverse events and high adherence in all of the food allergen trials were reported.

Conclusions

Overall, the EPIT study results, even if they were affected by great heterogeneity among the methodologies applied, have shown not only the high safety and adherence with this kind of immunotherapy but also suggested the possibility for obtaining definitive evidence of the efficacy of EPIT, especially for food allergies.

Safety and efficacy of epicutaneous immunotherapy for food allergy

Food allergy is increasingly common in children, affecting about 4%-8%. The mainstays of management remain allergen avoidance and emergency preparedness to treat allergic reactions with emergency medications. Unfortunately, these approaches are unsatisfactory for many patients and their families as the restrictions, constant vigilance, and unpredictable severity of allergic reactions negatively impact quality of life. In recent decades, there has been significant interest in developing treatments for food allergy that lead to desensitization to increase thresholds for triggering allergic reactions and decrease the risk of reacting to allergen-contaminated food products. Epicutaneous immunotherapy (EPIT) is a novel therapy that is currently under investigation, delivering allergen via repeated applications to the skin and targeting antigen-presenting cells in the superficial skin layers. Murine models have demonstrated that allergen uptake is an active process by skin dendritic cells with subsequent migration to draining lymph nodes. Allergen exposure to the non-vascularized epidermis limits systemic absorption, contributing to the high-safety profile. Results from murine experiments showed that EPIT has comparable efficacy as subcutaneous immunotherapy in terms of challenge outcomes, airway hyper-responsiveness, and immunologic parameters. Several clinical trials of EPIT have recently been completed or are ongoing. Results support the high safety and tolerability of this approach. Efficacy data suggest that the change in threshold eliciting dose following 1 year of therapy is less than that seen compared to high-dose (2-4 g peanut protein) oral immunotherapy, but more prolonged treatment with EPIT appears to lead to increasing desensitization. Additional data from larger-scale studies should provide a more robust assessment of safety and efficacy of EPIT.